Who Really Needs to Be Gluten-Free?

The gluten-free craze is unlikely to go away anytime soon. Many people say they feel better after adopting a diet free of gluten, a protein found in wheat, barley and rye, even though relatively few gluten avoiders have been given diagnoses of celiac disease, an autoimmune condition that can attack the intestines and other tissues when gluten is consumed.

Approximately one person in 140 is known to have celiac disease, which can remain silent for decades and become apparent at any age. The true incidence may be a lot higher. In a Denver study that followed children born from 1993 through 2004 into their teen years, 3.1 percent turned out to have celiac disease.

“That’s an unbelievable number of Americans who may be affected,” said Dr. Joseph A. Murray of the Mayo Clinic, an international expert on the disease.

While the health consequences of celiac disease have been well documented, other reasons a person’s health might be improved by avoiding gluten include a sensitivity to gluten or something else in wheat (the major source of gluten in Western diets) and the placebo effect — a genuine benefit inspired by the belief that a chosen remedy actually works.

Gluten sensitivity does not cause the intestinal and other organ damage wrought by celiac disease, although people with it tend to experience an array of symptoms. The health of three members of my family with non-celiac gluten sensitivity improved significantly when they eliminated gluten; one, who had struggled in vain for nearly a decade to lose weight, lost 40 pounds easily when she cut gluten from her diet.

Despite the current focus on gluten, there are probably many people walking around with celiac disease who don’t know they have it. The disorder can induce a host of vague and often confusing symptoms, the true cause of which may not be determined for a decade or longer. Among possible symptoms: abdominal pain, bloating, gas, chronic diarrhea, or constipation; chronic fatigue, anemia, unexplained weight loss, or muscle cramps; missed periods, infertility or recurrent miscarriage; vitamin deficiencies, discolored tooth enamel, bone loss and fractures.

Some people assume that the way they feel is normal and never mention their distress to a doctor, or if they do, doctors may dismiss the complaints as “nothing to worry about” or attribute them to another cause.

The fact is, however, that celiac disease can remain silent for many years, during which time hidden damage can occur with lifelong, sometimes irreversible, health effects. And as a report for the United States Preventive Services Task Force that reviewed the evidence recently stated, many of these “adverse health consequences” are “potentially avoidable.”

These factors suggest that a screening program to detect hidden disease might be health-saving for millions of people, especially children whose growth can be impaired and who may suffer other long-term problems from undiagnosed and untreated celiac disease.

However, after a thorough review of published reports, the task force did not endorse a screening program — not because it considers the condition not serious or because there is no screening test. Rather, the task force said, there is still not enough evidence to answer “key questions related to benefits and harms of screening for celiac disease in asymptomatic individuals.”

Among the areas that need more research, the task force concluded, are how accurate screening tests really are; whether screening and identifying people as having celiac disease can cause harm; and whether treating screen-detected disease improves the health, survival and quality of life of people who otherwise might not be treated.

The task force noted, for example, that no studies looked at the potential upside or downside of screening adults, adolescents or children who have no symptoms. The team concluded that a lot more well-designed research was needed before a screening recommendation could be justified as medically sound.

Meanwhile, millions of Americans are self-treating with gluten-free diets. This has its advantages and disadvantages. If avoiding gluten makes people feel better, if they can afford the sometimes more costly gluten-free foods, and if avoiding gluten doesn’t turn them into social pariahs, most reasonable people would say, “Why not?”

A main disadvantage of self-treatment without a diagnosis is that an accurate result of the tests for celiac disease requires that the person regularly consumes gluten. Avoiding this protein would mask a positive finding on a screening blood test and biopsy evidence of damage to the intestines that can result from eating gluten.

“There’s a simple blood test for celiac, but it must be done before you change your diet,” Dr. Murray said in an interview.

Aside from intestinal damage, failing to detect asymptomatic celiac at an early age can result in poor bone development and suppressed growth, Dr. Murray said. This can create “a high risk for fractures both before and after a diagnosis of celiac, which might not happen until age 40 or 50,” he explained.

When undiagnosed celiac results in persistent fatigue or infertility, “you can lose years of quality of life that you can’t get back,” Dr. Murray said.

If symptoms are subtle, he added, “people can be sick for so long, they don’t know what health is. They don’t recognize their symptoms and don’t complain to the doctor. If the whole population were screened and people with celiac were found and treated, it could result in no health consequences.”

That, however, would require rigorous adherence to a gluten-free diet. Without a medical diagnosis of celiac and an explanation of its possible consequences, people are likely to be less careful about what they eat.

There is also a potential medical downside to diagnosis and treatment. “Contrary to what many people think, a gluten-free diet is not necessarily a healthy diet,” Dr. Murray said. “When people with celiac go on it, they often gain weight, especially fat weight, because they are no longer malabsorbing nutrients. They are also more likely to develop metabolic syndrome,” which raises the risk of heart disease and Type 2 diabetes.

Until evidence is developed that could justify screening the entire population for celiac, Dr. Murray advocates screening “everyone in the at-risk group,” which would include family members of celiac patients and everyone with Type 1 diabetes, premature osteoporosis and anemia, which may be signs of celiac disease. He also advised that people with chronic bloating, mouth ulcers, chronic headaches or fatigue should be tested.

Others who may be at risk for celiac include people with tingling or numbness in the arms and legs, thyroid disease, rheumatoid arthritis and Sjogren’s syndrome.

A version of this article appears in print on , on Page D5 of the New York edition with the headline: Who Really Needs to Be Gluten-Free?. Order Reprints | Today’s Paper | Subscribe